Source: http://www.abarim-publications.com/Meaning/Arad.html

🔼The name Arad in the Bible

The name Arad occurs in the Bible as the name of a man and of a city. The man is mentioned among the sons of Beriah of Benjamin (1 Chronicles 8:15). The city called Arad lies in the southern extremity of Israel, in the Negev (according to Numbers 21:1).

When the Canaanite king of Arad draws out into battle against Israel and takes a few men captive, Israel retaliates by destroying the local Canaanites, Arad and other cities. Thus the place is renamed Hormah (Numbers 21:3). Arad, however survives, and is later mentioned among the towns conquered by Joshua (Joshua 12:14). Arad still exists as a reference point at the beginning of the time of the judges (Judges 1:16).

In the first half of the nineteenth century, Edward Robinson and Eli Smith identified modern day Tel Arad as the ancient city of Arad. Since then excavations have unearthed important inscriptions on ostraca from Arad. The Oxford Companion to the Bible reports that in Arad an ostracon was found which "implies an imminent attack from the direction of Edom".

🔼Etymology of the name Arad

The name Arad looks like it's a clean offshoot from an off the shelf Hebrew root ערד. The only problem is: that root does not exist: